
<h1><span class="yiyi-st" id="yiyi-12">numpy.diag</span></h1>
        <blockquote>
        <p>原文：<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.diag.html">https://docs.scipy.org/doc/numpy/reference/generated/numpy.diag.html</a></p>
        <p>译者：<a href="https://github.com/wizardforcel">飞龙</a> <a href="http://usyiyi.cn/">UsyiyiCN</a></p>
        <p>校对：（虚位以待）</p>
        </blockquote>
    
<dl class="function">
<dt id="numpy.diag"><span class="yiyi-st" id="yiyi-13"> <code class="descclassname">numpy.</code><code class="descname">diag</code><span class="sig-paren">(</span><em>v</em>, <em>k=0</em><span class="sig-paren">)</span><a class="reference external" href="http://github.com/numpy/numpy/blob/v1.11.3/numpy/lib/twodim_base.py#L244-L312"><span class="viewcode-link">[source]</span></a></span></dt>
<dd><p><span class="yiyi-st" id="yiyi-14">提取对角线或构造对角数组。</span></p>
<p><span class="yiyi-st" id="yiyi-15">如果您使用此函数提取对角线并希望写入生成的数组，请参阅<code class="docutils literal"><span class="pre">numpy.diagonal</span></code>的更详细的文档；是否返回一个副本或视图取决于你使用的numpy版本。</span></p>
<table class="docutils field-list" frame="void" rules="none">
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<col class="field-body">
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<tr class="field-odd field"><th class="field-name"><span class="yiyi-st" id="yiyi-16">参数：</span></th><td class="field-body"><p class="first"><span class="yiyi-st" id="yiyi-17"><strong>v</strong>：array_like</span></p>
<blockquote>
<div><p><span class="yiyi-st" id="yiyi-18">如果<em class="xref py py-obj">v</em>是2-D数组，则返回其<em class="xref py py-obj">k</em>对角线的副本。</span><span class="yiyi-st" id="yiyi-19">如果<em class="xref py py-obj">v</em>是1-D数组，则在<em class="xref py py-obj">k</em>对角线上返回具有<em class="xref py py-obj">v</em>的2-D数组。</span></p>
</div></blockquote>
<p><span class="yiyi-st" id="yiyi-20"><strong>k</strong>：int，可选</span></p>
<blockquote>
<div><p><span class="yiyi-st" id="yiyi-21">有问题的对角线。</span><span class="yiyi-st" id="yiyi-22">默认值为0。</span><span class="yiyi-st" id="yiyi-23">对于主对角线上方的对角线使用<em class="xref py py-obj">k&gt; 0</em>，对于主对角线下方的对角线使用<em class="xref py py-obj">k 。</em></span></p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name"><span class="yiyi-st" id="yiyi-24">返回：</span></th><td class="field-body"><p class="first"><span class="yiyi-st" id="yiyi-25"><strong>out</strong>：ndarray</span></p>
<blockquote class="last">
<div><p><span class="yiyi-st" id="yiyi-26">提取的对角线或构造的对角数组。</span></p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
<div class="admonition seealso">
<p class="first admonition-title"><span class="yiyi-st" id="yiyi-27">也可以看看</span></p>
<dl class="last docutils">
<dt><span class="yiyi-st" id="yiyi-28"><a class="reference internal" href="numpy.diagonal.html#numpy.diagonal" title="numpy.diagonal"><code class="xref py py-obj docutils literal"><span class="pre">diagonal</span></code></a></span></dt>
<dd><span class="yiyi-st" id="yiyi-29">返回指定的对角线。</span></dd>
<dt><span class="yiyi-st" id="yiyi-30"><a class="reference internal" href="numpy.diagflat.html#numpy.diagflat" title="numpy.diagflat"><code class="xref py py-obj docutils literal"><span class="pre">diagflat</span></code></a></span></dt>
<dd><span class="yiyi-st" id="yiyi-31">创建一个2-D数组，将扁平输入作为对角线。</span></dd>
<dt><span class="yiyi-st" id="yiyi-32"><a class="reference internal" href="numpy.trace.html#numpy.trace" title="numpy.trace"><code class="xref py py-obj docutils literal"><span class="pre">trace</span></code></a></span></dt>
<dd><span class="yiyi-st" id="yiyi-33">沿对角线求和。</span></dd>
<dt><span class="yiyi-st" id="yiyi-34"><a class="reference internal" href="numpy.triu.html#numpy.triu" title="numpy.triu"><code class="xref py py-obj docutils literal"><span class="pre">triu</span></code></a></span></dt>
<dd><span class="yiyi-st" id="yiyi-35">数组的上三角形。</span></dd>
<dt><span class="yiyi-st" id="yiyi-36"><a class="reference internal" href="numpy.tril.html#numpy.tril" title="numpy.tril"><code class="xref py py-obj docutils literal"><span class="pre">tril</span></code></a></span></dt>
<dd><span class="yiyi-st" id="yiyi-37">数组的下三角形。</span></dd>
</dl>
</div>
<p class="rubric"><span class="yiyi-st" id="yiyi-38">例子</span></p>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">x</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">arange</span><span class="p">(</span><span class="mi">9</span><span class="p">)</span><span class="o">.</span><span class="n">reshape</span><span class="p">((</span><span class="mi">3</span><span class="p">,</span><span class="mi">3</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">x</span>
<span class="go">array([[0, 1, 2],</span>
<span class="go">       [3, 4, 5],</span>
<span class="go">       [6, 7, 8]])</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">np</span><span class="o">.</span><span class="n">diag</span><span class="p">(</span><span class="n">x</span><span class="p">)</span>
<span class="go">array([0, 4, 8])</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">np</span><span class="o">.</span><span class="n">diag</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">k</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span>
<span class="go">array([1, 5])</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">np</span><span class="o">.</span><span class="n">diag</span><span class="p">(</span><span class="n">x</span><span class="p">,</span> <span class="n">k</span><span class="o">=-</span><span class="mi">1</span><span class="p">)</span>
<span class="go">array([3, 7])</span>
</pre></div>
</div>
<div class="highlight-default"><div class="highlight"><pre><span></span><span class="gp">&gt;&gt;&gt; </span><span class="n">np</span><span class="o">.</span><span class="n">diag</span><span class="p">(</span><span class="n">np</span><span class="o">.</span><span class="n">diag</span><span class="p">(</span><span class="n">x</span><span class="p">))</span>
<span class="go">array([[0, 0, 0],</span>
<span class="go">       [0, 4, 0],</span>
<span class="go">       [0, 0, 8]])</span>
</pre></div>
</div>
</dd></dl>
